In general, processing of a silver halide black-and-white photographic light-sensitive material includes black-and-white developing after imagewise exposing, fixing and rinsing and the processing of a silver halide color photographic light-sensitive material (hereinafter referred to as a color light-sensitive material) includes a color developing after imagewise exposing, desilvering, rinsing and stabilizing. Processing of a silver halide color reversal light-sensitive material includes black-and-white developing after imagewise exposing, color developing after reversal processing, desilvering, rinsing and stabilizing.
In a color developinq step, exposed silver halide grains are reduced to silver by a color developing agent. At the same time, the oxidation product of the color developing agent reacts with a coupler to form a dye image.
In a subsequent desilvering step, the developed silver obtained in the developing step is oxidized by a bleaching agent to obtain a silver salt (bleaching), and is further removed from a light-sensitive layer together with unexposed silver halide by a fixing agent which forms a soluble silver salt therewith (fixing). The bleaching and fixing may be carried out independently in a separate bleaching and fixing steps, or may be carried out simultaneously in a bleach-fixing step. The details of these processing steps and the compositions thereof are described in James, The Theory of Photographic Process, 4th Edition (1977), and Research Disclosure No. 17643, pp. 28 to 29, No. 18716, 651, from the left column to right column, and RD No.307105, pp. 880 to 881.
In addition to the above fundamental processing steps, various auxiliary steps may be carried out supplementally for maintaining the photographic and physical quality of a dye image or to promote processing stability. Such auxiliary steps include, for example, a rinsing step, a stabilizing step, a hardening step and a terminating step.
In general, the above processing steps are carried out in an automatic developing machine. Photographic processing is carried out in various places ranging from a large size processing laboratory, equipped with a large size automatic developing machine, to a retail photo store called a mini lab equipped with a small size automatic developing machine. Such versatility tends to be accompanied by a reduction in processing performance. The presence of metal ions in the processing solution is a major cause thereof. Various metal ions are introduced into the processing solution in a number of different ways. For example, calcium and magnesium may be introduced through water used to prepare a processing solution. Iron in some cases, and calcium contained in gelatin may leach into the processing solution. Furthermore, a bleach-fixing solution containing an iron chelate may be splashed into the preceeding developing bath. In some cases, the processing solution absorbed by a film contaminates a succeeding bath. The effect of carry over depends on the kind of involved ion and processing solution.
Calcium and magnesium ions introduced into a developing solution react with carbonate salt contained herein for use as a buffer agent to generate a precipitate and sludge, which clogs the filter of a circulating system of a developing machine and results in process staining of the film. Furthermore, when a transition metal salt such as iron ion is introduced into the developing solution, a marked deterioration of a photographic property results due to decomposition of paraphenylenediamine type color developing agents, black-and-white developing agents such as hydroquinones, and preservatives such as hydroxylamines and sulfate.
Also, introduction of a transition metal such as iron ion into a bleaching solution containing hydrogen peroxide and persulfate markedly deteriorates stability of the solution and results in a diminished bleaching capacity.
Also, in a fixing solution typically containing thiosulfate, the introduction of a transition metal salt deteriorates the stability of the fixing solution to generate turbidity and sludge therein. As a result, the circulating flow amount is reduced due to clogging of the filter of an automatic developing machine to reduce fixing capacity and generate processing stain on the film. Such phenomena as described for the fixing solution also occurs in rinsing water following the fixing solution. Especially, reduction in the amount of rinsing water reduces the solution exchange rate in the rinsing tank, to remarkably decompose thiosulfate (called sulfurization) with the resulting precipitation of silver sulfide. Under such circumstances, the film surface is liable to be stained to the extent that it loses its commercial value.
In a stabilizing solution prepared using hard water containing calcium and magnesium in large quantity, bacteria proliferate by consuming these elements as a nutrient to generate turbidity in the solution and cause film staining.
Transition metal ions introduced into the processing solution including iron ion cause various adverse effects and accordingly, there is a demand of an effective masking agent for metal ions.
A chelating agent for masking metal ions has hithereto been proposed as a method for solving the above problems. Examples thereof include, for example, aminocarboxylic acids (for example, ethylenediaminetetracetic acid and ethylenetriaminepentacetic acid) described in JP-B-48-30496 and 44-30232 (the term "JP-B" as used herein means an examined Japanese patent publication), organic phosphonic acids described in JP-A-56-97347 (the term "JP-A" as used herein means an unexamined published Japanese patent application), JP-B-56-39359, and German Patent 2,227,639, phosphonocarboxylic acids described in JP-A-52-102726, 53-42730, 54-121127, 55-126241, and 55-65956, and other compounds described in JP-A-58-195845 and 58-203440, and JP-B-53-40900.
The above described compounds are inadequate, although some are of practical use. For example, while ethylenediaminetetraacetic acid has a large masking ability against calcium ion, the subject chelating agent accelerates decomposition of a developing agent and preservative therefor in the presence of iron ion when added to the developing solution. This results in deterioration of photographic properties, such as reduction of image density and an increase in fog. Also, for example, while alkylidenediphosphonic acid exerts no such adverse effects even in the presence of iron ion, the subject chelating agent undesirably generates solid materials in a processing solution prepared with hard water containing calcium in large quantity to cause machine malfunction.
Especially in recent years, and in view of environmental considerations, the replenishing amount of photographic processing solutions has been progressively decreased with an accompanying increase in the residence time of the processing solutions in an automatic processor. Accordingly, the preservability of processing solutions is becoming increasingly more important. For this reason, the development of a technology has been desired in which the metal ions are effectively masked without otherwise adversely affecting the processing solution.
Furthermore, with the greater availability of mini labs for processing color light-sensitive materials, rapid processing service at the retail level is becoming popular. However, satisfactory rapid bleaching has not yet been achieved despite the use of a bleach accelerating agent (for example, the addition of the mercapto compounds described in U.S. Pat. No. 1,138,842), because ethylenediaminetetracetic acid ferric complex salt widely used as a bleaching agent in the bleaching step and bleach-fixing step disadvantageously has a weak oxidizing power.
While red prussiate, iron chloride and bromate are known as bleaching agents which achieve rapid bleaching, red prussiate is unsatisfactory in view of environmental conservation, iron chloride poses handling problems such as metal corrosion, and bromate forms an unstable solution.
Accordingly, there is a demand for a bleaching agent which is easy to handle and achieves rapid bleaching, and which does not pose a problem in disposing of a waste solution thereof. Recently, 1,3-diaminopropanetetracetic acid ferric complex salt has been proposed as a bleaching agent capable of satisfying these conditions. However, the proposed bleaching agent causes bleaching fog. The addition of a buffer agent to the bleaching solution has been proposed as a method for reducing this bleaching fog (for example, JP-A-1-213657). However, the improvement in bleaching fog is not adequate. Particularly in rapid processing in which color development is carried out in three minutes or less, bleaching fog is generated to even a greater extent because a developing solution having a high activity is used.
Furthermore, the use of a processing solution having a bleaching ability comprising this 1,3-diaminopropanetetraacetic acid ferric complex salt, results in increased stain during the storage after processing.
Furthermore, the desilvering property is considerably reduced in continuous processing carried out with a processing solution having a bleaching ability comprising a 1,3-diaminopropanetetracetic acid ferric complex salt, in comparison with the initial stage of the continuous processing. A precipitate is also formed.
Accordingly, there is a demand for a processing composition having a bleaching ability and processing method using the same which solves the above described problems.
Furthermore, in view of environmental considerations, the ability to convert a photographic processing waste solution to a non-hazardous form, and especially one that is readily subjected to biodegradation, is highly desired. The polycarboxylic acid derivatives derived from o-aminophenol are proposed as such a compound in German Patent Publication 3,912,551. However, it has been found that the desilvering property is considerably reduced in continuous processing carried out with a processing solution having a bleaching ability comprising a ferric complex salt of this compound, in comparison with the initial stage of the continuous processing. Also, bleaching fog and stain are still present.
Furthermore, in view of environmental conservation, there has been a demand for a reduction in the concentration of the metal chelating compound. However, sufficient desilvering property is not obtained with conventional bleaching agents of a diluted concentration.